System and method for controlling a fluid pump

ABSTRACT

A system for controlling operation of a fluid pump includes a pressure sensor operably coupled to a fluid gun and a controller operably coupled to the pressure sensor. The controller is configured to receive an input indicative of a desired pressure at the fluid gun. The controller is also configured to receive a signal indicative of pressure at the fluid gun. The controller is further configured to determine a desired gear of a transmission operably coupled to the fluid pump based on a desired operating speed of the fluid pump. The controller is also configured to operate the transmission in the desired gear to substantially achieve the desired pressure at the fluid gun.

TECHNICAL FIELD

The present disclosure relates generally to systems and methods for controlling a fluid pump and, more particularly, to systems and methods for controlling a fluid pump for delivering fluid to a nozzle.

BACKGROUND

Pressurized fluid may be used for performing a number of tasks. For example, pressurized fluid may be used to clean the surfaces of a wide variety of objects, such as, for example, houses, aircraft, and automobiles. During such use, pressurized fluid (e.g., water) is discharged against the surface and the force of the discharged fluid acts to remove dirt and grit from the surface. Pressurized fluid may also be used for removing the ice from portions of an aircraft, such as for example, aircraft wings. During such uses, the pressurized fluid may reach pressures ranging from 10,000 to 20,000 psi.

Conventional systems for providing a pressurized discharge of fluid often include a power source coupled to a fluid pump via a transmission, such that the power source drives the transmission, which, in turn, drives the fluid pump. The fluid pump delivers fluid through a fluid line to a nozzle including an orifice for emitting a pressurized discharge of the fluid. In conventional systems, the power source may often include an internal combustion engine and the transmission may include a number of gears for selectively providing different gear ratios to drive the fluid pump at different operating speeds. The fluid pump in the conventional system often includes a reciprocating plunger pump. Such fluid pumps have an output directly proportional to the speed at which they are driven and the size of the plunger, which reciprocates in order to deliver fluid to the nozzle. As a result, the pressure of the fluid discharged from the nozzle orifice depends on the speed at which the fluid pump is driven, the plunger size, and the nozzle orifice size. The plunger size and/or nozzle orifice size may often be changed to achieve a desired discharge pressure.

There are a number of possible drawbacks that may be associated with conventional systems for providing a pressurized discharge of fluid. For example, since the pressure of the fluid discharged from the nozzle orifice is directly proportional to the speed at which the fluid pump is driven, in order to achieve and maintain a desired pressure, the proper speed of the internal combustion engine and the proper gear ratio of the transmission must be selected to achieve the desired pressure. Achieving the desired pressure, however, may require a relatively large number of engine speed adjustments and/or transmission gear changes. Such adjustments and/or gear changes may necessitate operation of conventional systems by relatively skilled operators in order to achieve and/or maintain the desired pressure. Furthermore, changing transmission gears may result in pressure spikes that may increase the wear of system components, thereby reducing the service life of those components. Additionally, due to numerous possible manual adjustments to the engine speed and gear selection, it may require an undesirably long period of time to achieve a desired pressure once operation is initiated.

Another possible drawback with conventional systems relates to adjustments in the desired pressure. For example, in some conventional systems, the plunger size and/or nozzle orifice size may be changed in order to achieve an alternative desired system performance. As a result, the internal combustion engine speed and/or the transmission gear ratio may need to be changed in order to account for such changes in the plunger and/or nozzle. As outlined above, a skilled operator may be necessary in order make necessary adjustments to achieve desired system performance and/or may require numerous adjustments to the internal combustion engine speed and or transmission gear selection, which may lead to pressure spikes often associated with increased component wear.

Another possible drawback with conventional systems relates to the fact that conventional plungers and nozzle orifices wear. Since the plunger size and/or nozzle orifice size have a direct effect on the pressure of the discharged fluid, conventional systems may require numerous adjustments to account for such wear. Such adjustments may necessitate a skilled operator and/or may result in numerous engine speed and/or transmission gear changes in order to achieve desired system performance.

An example of a water blasting system including a pressure control is described in U.S. Pat. No. 5,848,877 (the '877 patent) issued to Dill et al. on Dec. 15, 1998. The '877 patent describes a high pressure system for outputting pressurized fluid to a blasting gun. The system includes a mechanical transmission interconnecting a diesel engine with a positive displacement pump. A programmable controller is provided for receiving signals from a pressure transducer located on the pump indicative of a pressure output from the pump and for controlling operation of an engine controller, a clutch controller, and a transmission shifter to obtain the desired fluid pressure level output from the pump based on an operating pressure signal received from the pressure transducer located on the pump. The controller may be operated to automatically shift the transmission in response to fluid pressure output from the pump. Alternatively, the controller may receive input instructions from an operator to shift the transmission to a desired gear. The controller automatically regulates engine speed and engages and disengages the clutch for automatically shifting the transmission.

Although the system described in the '877 patent may automatically regulate engine speed and engage and disengage a clutch for shifting a transmission, the system still suffers from many of the drawbacks outlined above, such as, for example, excessive transmission shifting, failure to compensate for different plungers and/or nozzle orifice sizes, and/or failure to compensate for plunger and/or nozzle orifice wear.

The disclosed systems and methods for controlling a pump are directed to overcoming one or more of the drawbacks set forth above.

SUMMARY OF THE INVENTION

In one aspect, the present disclosure includes a system for controlling operation of a fluid pump. The system includes a pressure sensor operably coupled to a fluid gun and a controller operably coupled to the pressure sensor. The controller is configured to receive an input indicative of a desired pressure at the fluid gun. The controller is also configured to receive a signal indicative of pressure at the fluid gun. The controller is further configured to determine a desired gear of a transmission operably coupled to the fluid pump based on a desired operating speed of the fluid pump. The controller is also configured to operate the transmission in the desired gear to achieve the desired pressure at the fluid gun.

In a further aspect, the present disclosure includes a system for discharging pressurized fluid. The system includes a power source configured to supply torque and a transmission operably coupled to the power source. The transmission includes a plurality of gears having different gear ratios. The system also includes a fluid pump operably coupled to the transmission. The fluid pump is configured to supply fluid to a fluid gun. The system further includes a fluid gun operably coupled to the fluid pump. The fluid gun is configured to discharge pressurized fluid. The system also includes a pressure sensor operably coupled to the fluid gun and a controller operably coupled to at least one of the power source and the transmission. The controller is configured to receive an input indicative of a desired pressure at the fluid gun and receive a signal indicative of pressure at the fluid gun. The controller is also configured to determine a desired operating speed of the fluid pump based on the desired pressure at the fluid gun and the signal indicative of pressure at the fluid gun. The controller is further configured to determine a desired gear of the transmission based on the desired operating speed of the fluid pump and control operation of at least one of the power source and the transmission such that the desired pressure at the fluid gun is substantially achieved.

In still a further aspect, the present disclosure includes a method of controlling a fluid pump. The method includes receiving an input indicative of a desired pressure at a fluid gun operably coupled to the fluid pump. The method also includes receiving from a pressure sensor a signal indicative of pressure at the fluid gun as the pressure at the fluid gun rises upon activation of a power source operably coupled to the fluid pump via a transmission including a plurality gears. The method further includes determining a desired operating speed of the fluid pump based on the desired pressure at the fluid gun and the signal indicative of pressure at the fluid gun. The method also includes determining a desired gear of the transmission based on the desired operating speed of the fluid pump and operating the transmission in the desired gear to substantially achieve the desired pressure at the fluid gun.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram of an exemplary system for discharging pressurized fluid; and

FIG. 2 is a schematic block diagram of an exemplary control scheme for controlling a fluid pump.

DETAILED DESCRIPTION

FIG. 1 schematically depicts an exemplary embodiment of a system 10 for discharging pressurized fluid. System 10 may include a power source 12 operably coupled to a transmission 14, which is configured to supply torque to a fluid pump 16. Fluid pump 16 may be operably coupled to a fluid gun 18 configured to discharge pressurized fluid.

Power source 12 may be, for example, an internal combustion engine, an electric motor, and/or a hydraulic motor. For example, power source 12 may be a compression ignition engine. Other types of power sources known to a person having skill in the art may be used. Power source 12 may be operably coupled to transmission 14 via a coupling device 20 configured to transfer mechanical energy supplied by power source 12 to transmission 14. Power source 12 may include, for example, an output shaft 22 operably coupled to a flywheel 24, and coupling device 20 may include, for example, a lock-up clutch 26 and torque converter 28. Torque converter 28 may be configured to match the speed of rotation of output shaft 22 to the speed of rotation of an input shaft 30 of transmission 14 via, for example, a viscous coupling. Lock-up clutch 26 may be selectively activated so that transfer of mechanical energy from output shaft 22 may be directly transferred to input shaft without relying on the viscous coupling of torque converter 28, which may result in more efficient operation of coupling device 20. Other types of coupling devices known to a person having skill in the art may be used, such as, for example, a coupling device having a clutch but no torque converter.

Transmission 14 may include a transmission output shaft 32 and a number of gears (e.g., six gears). The gears may be changed in order to alter the ratio of the rotational speed of input shaft 30 of transmission 14 to the rotational speed of transmission output shaft 32. Alternatively, rather than having a number of gears, transmission 14 may be a continuously variable transmission or any type of transmission known to a person having skill in the art.

Transmission output shaft 32 may be operably coupled to fluid pump 16 via, for example, a flexible coupling 34. Flexible coupling 34 may, in turn, be operably coupled to fluid pump 16 via, for example, a belt drive 36, which may include a drive pulley 38 coupled to an output pulley 40 via a drive belt 42. Fluid pump 16 may operate, for example, at a speed proportional to the speed of transmission output shaft 32. Output pulley 40 may be operably coupled to fluid pump 16 via a fluid pump drive shaft 44.

Fluid pump 16 is configured to supply fluid to fluid gun 18 via a fluid hose 46. Fluid hose 46 may include, for example, high-pressure tubing such as, for example, braided high-pressure tubing, and fluid pump 16 may be a reciprocating pump, a scroll pump, a centrifugal pump, a variable displacement pump, or an axial flow pump. For example, fluid pump 16 may be a reciprocating pump including, for example, one or more plungers configured to pump fluid from a fluid supply (not shown) to fluid gun 18. The one or more plungers may be replaced by different plungers such that the fluid pumping characteristic (e.g., the flow rate for a given fluid pump speed and fluid viscosity) of fluid pump 16 is altered. Other types of fluid pumps and fluid hoses known to a person having skill in the art may be used.

Fluid gun 18 may be a trigger gun and may include a trigger 48 and a nozzle 50 defining a nozzle orifice 52. Trigger 48 may be configured to selectively control discharge of fluid through nozzle 50 and out nozzle orifice 52. Nozzle 50 may be selectively replaced with nozzles having different discharge characteristics, such as, for example, nozzles having different size nozzle orifices. Other types of fluid guns known to a person having skill in the art may be used.

System 10 may further include a controller 54 configured to control the operation of, for example, power source 12, lock-up clutch 26, and/or transmission 14. For example, controller 54 may be configured to receive inputs from an input device 56, a power source sensor 58, a transmission gear sensor 60, a transmission speed sensor 62, and/or a pressure sensor 64 configured to measure the pressure at fluid gun 18, which may be indicative of the pressure of the pressurized fluid discharged from fluid gun 18. For example, controller 54 may be configured to receive via input device 56, a desired pressure for fluid discharged by fluid gun 18 that may be entered, for example, by an operator of system 10. Alternatively, a desired fluid pressure may be received from a remote location via, for example, wireless transmission. Further, controller 54 may be configured to receive power source speed information from power source sensor 58, transmission gear selection information from transmission gear sensor 60, pump speed based on information from transmission speed sensor 62, and/or fluid pressure information from pressure sensor 64. Controller 54 may also be configured to output control commands such as, for example, power source speed control commands to power source 12, lock-up clutch engagement/disengagement commands to lock-up clutch 26, and/or transmission gear shift commands to transmission 14.

INDUSTRIAL APPLICABILITY

The disclosed systems and methods for controlling a pump may have application for controlling any type of pump. For example, the exemplary systems and methods may be applicable for controlling a pump for delivering fluid to a nozzle configured to discharge pressurized fluid. For example, the exemplary systems and methods may be used to clean the surfaces of a wide variety of objects, such as, for example, houses, aircraft, and automobiles. In particular, during such uses, pressurized fluid (e.g., water) may be discharged against the surface and the force of the discharged fluid may act to remove dirt and grit from the surface. Pressurized fluid may also be used for removing the ice from portions of an aircraft, such as, for example, aircraft wings. During such uses, the pressurized fluid may reach pressures ranging from, for example, 10,000 to 20,000 psi.

The exemplary systems and methods may be applicable to controlling a pump for delivering fluid to a nozzle configured to discharge pressurized fluid in a manner that results in, for example, more rapid achievement of the desired discharge pressure upon start-up, thereby possibly enhancing productivity. Furthermore, the exemplary systems and methods may result in automatic adjustment of power source operating speed and/or automatic selection of transmission gears for different plungers, different nozzle orifices, and/or a combination thereof. In addition, the exemplary systems and methods may result in fewer necessary operator inputs, thereby enhancing ease of operation and reducing transmission gear changes, which my possibly reduce potentially damaging pressure spikes. The exemplary systems and methods may also provide automatic compensation for plunger and/or nozzle orifice wear, and/or may also result in extended power source and/or transmission service life due, for example, to more consistent operation in an appropriate transmission gear. By virtue of the exemplary systems and methods, one or more of these desired aspects may be achieved. The operation of exemplary system 10 will now be explained.

Referring to FIG. 1, exemplary system 10 for discharging pressurized fluid includes power source 12, which may be operably coupled to transmission 14, which supplies torque to fluid pump 16. Fluid pump 16 supplies fluid to fluid gun 18, which includes nozzle 50 having nozzle orifice 52, which is configured to provide a pressurized fluid discharge.

Power source 12 may be, for example, a compression ignition engine, which supplies torque to output shaft 22. In a torque converter drive mode, torque converter 28 of coupling device 20 operates to match the speed of rotation of output shaft 22 of power source 12 to the speed of rotation of input shaft 30 of transmission 14 via, for example, a viscous coupling. In a lock-up clutch drive mode, lock-up clutch 26 may be selectively activated, so that mechanical energy from the output shaft 22 may be directly transferred to input shaft 30 without relying on the viscous coupling of torque converter 28, which may result in a more efficient operation of system 10.

The gears of transmission 14 may be shifted in order to alter the ratio of the rotational speed of input shaft 30 of transmission 14 to the rotational speed of transmission output shaft 32. Transmission output shaft 32 may supply torque to fluid pump 16 via, for example, flexible coupling 34 and belt drive 36. For example, flexible coupling 34 may supply torque to drive pulley 38, which is coupled to output pulley 40 via drive belt 42. Output pulley 40 is operably coupled to fluid pump 16's drive shaft 44, which supplies torque to fluid pump 16, for example, such that the operating speed of fluid pump 16 is proportional to the speed of transmission output shaft 32.

Using torque supplied by fluid pump 16's drive shaft 44, fluid pump 16 supplies fluid to fluid gun 18 via fluid hose 46. Fluid pump 16 may be, for example, a reciprocating pump, which converts rotational energy of drive shaft 44 into reciprocating motion of, for example, one or more plungers, which pump fluid to fluid gun 18. The one or more plungers may be changed, such that the fluid pumping characteristic (e.g., the flow rate for a given fluid pump speed and fluid viscosity) of fluid pump 16 is altered.

Fluid gun 18 may be activated by depressing trigger 48, such that fluid received from fluid pump 16 flows to nozzle 50 and is discharged through nozzle orifice 52. The magnitude of the pressure of the fluid discharged from nozzle orifice 52 is directly related to the size and/or configuration of nozzle orifice 52 and/or the flow rate of the fluid received from fluid pump 16. For example, if fluid pump 16 operates at a higher speed, fluid is delivered to fluid gun 18 at a higher rate, thereby creating a potential for generating a higher pressure fluid discharge. Further, using a nozzle 50 having a smaller nozzle orifice 52 results in generating a higher pressure discharge for a given fluid delivery rate. On the other hand, if fluid pump 16 operates at a lower speed, fluid is delivered to fluid gun 18 at a lower rate, thereby reducing the potential for generating a higher pressure fluid discharge, and using a nozzle 50 having a larger nozzle orifice 52 results in generating a fluid discharge having a lower pressure for a given fluid delivery rate.

Exemplary system 10 depicted in FIG. 1 further includes a controller 54 configured to control the operation of power source 12, lock-up clutch 26, and/or transmission 14. For example, controller 54 receives via inputs from input device 56, a desired pressure for fluid discharged by fluid gun 18, which may be manually entered by an operator of system 10. Alternatively, a desired fluid pressure may be received from a remote location via, for example, wireless transmission. The desired pressure for fluid discharged from fluid gun 18 may be input into controller 54 via other sources known to a person having skill in the art, such as for example, via a computer. Further, controller 54 may receive power source speed information from power source sensor 58, transmission gear selection information from transmission gear sensor 60, pump speed information based on information from transmission speed sensor 62, and/or fluid pressure information from pressure sensor 64. Controller 54 may output power source speed control commands to power source 12, lock-up clutch engagement/disengagement commands to lock-up clutch 26, and/or transmission shift gear shift commands to transmission 14, for example, to control the characteristics of the pressurized fluid discharged from fluid gun 18.

Referring to FIG. 2, controller 54 may operate as follows. For example, an operator may turn on system 10, which activates ignition at step 110, which, in turn, boots up an electronic control module of controller 54. Once ignition is activated, the operator may also enter into input device 56 a desired pressure for the fluid discharged from fluid gun 18 at step 112. Input device 56 may be any input device known to a person having skill in the art.

Furthermore, once the ignition has been activated at step 110, power source 12 may be started, for example, from a low idle speed at step 114. Once power source 12 establishes low idle speed, torque converter drive mode may be activated in, for example, first gear of transmission 14 at step 116.

As power source 12 supplies torque to transmission 14, coupling device 20 drives transmission output shaft 32 via viscous coupling while in torque converter drive mode with transmission 14 in, for example, first gear. As transmission output shaft 32 drives fluid pump 16, fluid pressure begins to build in system 10. When, for example, the operator of system 10 depresses trigger 48 of fluid gun 18 for the first time following system ignition, pressurized fluid is discharged from fluid gun 18's nozzle orifice 52. As the pressurized fluid is initially discharged, the pressure drops. Thereafter, as power source 12 builds speed and drives fluid pump 16 at a faster rate, pressure of the pressurized fluid discharged from nozzle orifice 52 increases.

As the pressure at fluid gun 18 increases, controller 54 monitors system 10's pressure at step 118 and determines at step 120 a desired speed (e.g., a target speed) at which to drive fluid pump 16 in order to achieve the desired pressure received by controller 54. For example, controller 54 may receive pressure information from pressure sensor 64 and fluid pump speed information from transmission speed sensor 62 and may determine the rate of pressure increase at pressure sensor 64 relative to fluid pump speed. Based on this information, controller 54 may be able to estimate, for example, the characteristics of fluid pump 16 and/or nozzle 50. For example, controller 54 may be able to estimate the characteristics of the one or more plungers of fluid pump 16 (e.g., the plunger type number) and/or the characteristics of the nozzle orifice 52 (e.g., the nozzle orifice 52's size). These characteristics may be determined several ways.

For example, these characteristics may be determined by evaluating fluid flow equations (e.g., fluid flow equations derived from equations known to a person having skill in the art) that provide an indication of the characteristics of the plunger and/or the nozzle orifice. For example, as the speed of fluid pump 16 increases from 600 to 900 revolutions per minute (rpm), the pressure at fluid gun 18 indicated by pressure sensor 64 increases. Controller 54 evaluates a relationship between the rate of change of the pressure increase and the rate of change of fluid pump operating speed. This relationship may most closely correspond to one of the pressure rise equations for a given plunger type and/or nozzle orifice size. For a #12 plunger, for example, one such pressure rise equation may be y=0.0693x^(2.0095); where y corresponds to fluid pump torque in Newton-Meters, and x corresponds to fluid pump operating speed in rpm.

Once the corresponding pressure rise equation has been determined, a desired operating speed for fluid pump 16 may be determined based on the pressure rise equation and the desired pressure input at step 112. Alternatively, rather than using a pressure rise equation, controller 54 may evaluate look-up tables, which include, for example, empirical data of fluid flow characteristics for different plunger-type numbers, nozzle orifice sizes, and/or fluid pump speeds. Such equations and look-up tables may be stored in memory included in controller 54 and/or may be retrieved from a data base remote from controller 54 via, for example, wireless transmission. In this fashion, a desired operating speed for fluid pump 16 to achieve the desired pressure at fluid gun 18 may be determined at step 120.

Once the desired operating speed of fluid pump 16 has been determined at step 120, controller 54 may determine a desired gear selection for transmission 14 and/or a power source operating speed at step 122, such that fluid pump 16 may be operated at the desired operating speed determined at step 120. The desired gear and/or power source operating speed may be selected based on considerations, such as, for example, the most efficient fuel consumption and/or reduced exhaust emissions of power source 12. The desired gear and/or power source operating speed may be determined by evaluating look-up tables, which include, for example, empirical data of power source fuel efficiency and/or exhaust emissions for given power source operating speeds, and/or transmission output shaft speeds. For example, controller 54 may determine a desired gear selection for transmission 14 by using a look-up table that lists a desired gear selection based on a range of desired operating speeds for fluid pump 16 for each gear of transmission 14. Such look-up tables may be stored in memory in controller 54 and/or may be retrieved from a data base remote from controller 54 via, for example, wireless transmission. In this fashion, a desired gear may be selected for driving fluid pump 16, such that the desired pressure at fluid gun 18 may be achieved.

Once the desired gear has been determined, controller 54 may compare at step 124 the desired gear determined in step 122 with the gear in transmission 14 driving fluid pump 16 at that time, for example, based on information from transmission gear sensor 60. If controller 54 determines that transmission 14 is not in the same gear as the desired gear, controller 54 may operate to shift transmission 14 into the desired gear in step 126. This shift may be accomplished in a conventional manner known to a person having skill in the art. Once transmission 14 has been shifted to the desired gear, controller 54 may return to step 118 and repeat steps 120 through step 124, where controller 54 once again determines if transmission 14 is operating in the desired gear.

When controller 54 determines that transmission 14 is operating in the desired gear, controller 54 thereafter determines at step 128 whether fluid pump 16 is operating within a certain range of the desired operating speed determined at step 120. The desired operating range may be, for example, about 50 rpm, which may selected based on various considerations, such as, for example, a desired accuracy of the pressure of the pressurized fluid discharged from fluid gun 18.

If fluid pump 16 is being driven within the desired operating range, controller 54 may activate (e.g., engage) lock-up clutch 26 at step 130, such that transmission 14 operates in the lock-up drive mode rather than in the torque converter drive mode. This may result in more efficient operation of system 10 because, for example, there are no frictional losses that are often associated with viscous coupling operation.

Once controller 54 activates lock-up clutch 26, controller 54 may commence closed-loop operational control of power source speed at step 132 to maintain the desired pressure of pressurized fluid discharged from fluid gun 18. For example, controller 54 may monitor the pressure at fluid gun 18 via pressure sensor 64 and may control power source 12's speed to maintain the desired pressure at fluid gun 18, for example, without the need to shift gears of transmission 14.

If, on the other hand, at step 128 controller 54 determines that fluid pump 16 is not operating within the desired operating speed range, controller 54 maintains torque converter drive mode at step 134 and controller 54 adjusts power source speed and continues to monitor the pressure at fluid gun 18 received from pressure sensor 64 until fluid pump 16 is operating within the desired operating speed range at step 128, at which point controller 54 activates lock-up clutch 26 at step 130, so that system 10 operates in lock-up drive mode rather than torque converter drive mode. Thereafter, controller 54 may commence closed loop operational control of power source speed at step 132 to maintain the desired pressure at fluid gun 18, for example, as outlined previously herein.

Exemplary system 10 may operate with a number of desirable attributes. For example, by virtue of system 10 automatically determining an appropriate (e.g., an optimum) speed of fluid pump 16 based on the desired pressure at fluid gun 18, system 10 may automatically select an appropriate (e.g., an optimum) gear for transmission 14 and/or an appropriate (e.g., an optimum) operating speed for power source 12. This may result in only a single gear shift (e.g., at a very low system pressure) upon system activation and/or a relatively small number of speed adjustments for power source 12 and/or gear changes for transmission 14. As a result, system 10 may be operated by relatively unskilled operators while still achieving desired system performance. Furthermore, since changing transmission gears may result in pressure spikes that increase the wear rate of system components, system 10's ability to reduce the number of such shifts may increase the service life of those components. Additionally, since the number of manual adjustments to power source 12's speed and/or transmission 14's gear shifts may be substantially reduced, system 10 may achieve the desired operating pressure more quickly, thereby resulting in more efficient use. By virtue of controller 54 being able to automatically select power source 12's operating speed and/or transmission 14's gear selection, power source 12 may be able to operate with greater fuel efficiency and/or with reduced exhaust emissions.

As in some conventional systems, the plunger size and/or nozzle orifice size of system 10 may be changed in order to achieve desired alternative performance characteristics. With exemplary system 10, however, such changes may be automatically compensated for by virtue of system 10 being able to estimate plunger and/or nozzle characteristics. As a result, power source 12's speed and/or transmission 14's gear ratio may be automatically adjusted in order to account for such changes in plunger and/or nozzle. This may serve to reduce the skill level of the operator required to achieve desired system performance even when such changes are made to the plunger and/or nozzle. In addition, since system 10 may be able to estimate the plunger and/or the nozzle's characteristics, system 10 may automatically compensate for plunger and/or nozzle wear. In particular, since the plunger and/or nozzle orifice size have a direct effect on the pressure of the discharged fluid, conventional systems require adjustment to compensate for such wear. In particular, system 10 may compensate for such wear so that a skilled operator and/or numerous power source speed adjustments and/or transmission gear changes are not required in order to achieve desired system performance.

It will be apparent to those skilled in the art that various modifications and variations can be made to the exemplary embodiments disclosed. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed embodiments. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents. 

1. A system for controlling operation of a fluid pump, the system comprising: a pressure sensor operably coupled to a fluid gun; and a controller operably coupled to the pressure sensor, the controller being configured to receive an input indicative of a desired pressure at the fluid gun, receive a signal indicative of pressure at the fluid gun, determine a desired gear of a transmission operably coupled to the fluid pump based on a desired operating speed of the fluid pump, and operate the transmission in the desired gear to achieve the desired pressure at the fluid gun.
 2. The system of claim 1, wherein the controller is configured to determine the desired operating speed of the fluid pump based on the signal indicative of pressure at the fluid gun as the pressure rises upon activation of a power source supplying torque to the transmission.
 3. The system of claim 1, wherein the controller is configured to communicate with the transmission such that the transmission changes to the desired gear.
 4. The system of claim 1, wherein the system includes a plurality of equations indicative of a relationship between pressure at the fluid gun and fluid pump operating speed, and wherein the controller is configured to determine the desired operating speed of the fluid pump by selecting one of the plurality of equations that most closely corresponds to a relationship between the signal indicative of pressure at the fluid gun and the operating speed of the fluid pump.
 5. The system of claim 4, wherein the system includes a memory device, and the plurality of equations are stored in the memory device.
 6. The system of claim 5, wherein the controller includes the memory device.
 7. The system of claim 1, wherein the system includes a look-up table that lists a desired gear for each of a plurality of ranges of desired operating speeds of the fluid pump, and wherein the controller is configured to determine the desired gear via the look-up table based on the desired operating speed of the fluid pump.
 8. The system of claim 7, wherein the system includes a memory device, and the look-up table is stored in the memory device.
 9. The system of claim 8, wherein the controller includes the memory device.
 10. The system of claim 1, wherein the controller is configured to communicate with a lock-up clutch operably coupled to the transmission such that the lock-up is selectively activated.
 11. The system of claim 1, wherein the controller is configured to control operation of at least one of a power source and a transmission operably coupled to the power source and the fluid pump, such that the fluid pump operates at a speed within a range of the desired operating speed of the fluid pump.
 12. A system for discharging pressurized fluid, the system comprising: a power source configured to supply torque; a transmission operably coupled to the power source, the transmission including a plurality of gears having different gear ratios; a fluid pump operably coupled to the transmission, the fluid pump being configured to supply fluid to a fluid gun; a fluid gun operably coupled to the fluid pump, the fluid gun being configured to discharge pressurized fluid; a pressure sensor operably coupled to the fluid gun; and a controller operably coupled to at least one of the power source and the transmission, wherein the controller is configured to receive an input indicative of a desired pressure at the fluid gun, receive a signal indicative of pressure at the fluid gun, determine a desired operating speed of the fluid pump based on the desired pressure at the fluid gun and the signal indicative of pressure at the fluid gun, determine a desired gear of the transmission based on the desired operating speed of the fluid pump, and control operation of at least one of the power source and the transmission such that the desired pressure at the fluid gun is substantially achieved.
 13. The system of claim 12, wherein the controller is configured to determine the desired operating speed of the fluid pump based on the signal indicative of pressure at the fluid gun as the pressure at the fluid gun rises upon activation of the power source supplying torque to the transmission.
 14. The system of claim 12, wherein the controller is configured to communicate with the transmission such that the transmission changes to the desired gear.
 15. The system of claim 12, wherein the system includes a plurality of equations indicative of a relationship between pressure at the fluid gun and fluid pump operating speed, and wherein the controller is configured to determine the desired operating speed of the fluid pump by selecting one of the plurality of equations that most closely corresponds to a relationship between the signal indicative of pressure at the fluid gun and operating speed of the fluid pump.
 16. The system of claim 12, wherein the power source is operably coupled to the transmission via a coupling member, the coupling member including a torque converter and a lock-up clutch.
 17. The system of claim 16, wherein the controller is configured to selectively activate the lock-up clutch when the transmission is in the desired gear.
 18. The system of claim 12, wherein the fluid pump includes a reciprocating pump including at least one plunger.
 19. The system of claim 18, wherein the fluid gun includes a nozzle defining an orifice configured to discharge pressurized fluid, and wherein the controller is configured to determine the desired operating speed of the fluid pump by estimating characteristics of at least one of the plunger and the orifice.
 20. The system of claim 12, wherein the system includes a look-up table that lists a desired gear for each of a plurality of ranges of desired operating speeds of the fluid pump, and wherein the controller is configured to determine the desired gear via the look-up table based on the desired operating speed of the fluid pump.
 21. The system of claim 12, wherein the controller is configured to control operation of at least one of the power source and the transmission such that the fluid pump operates at a speed within a range of the desired operating speed of the fluid pump.
 22. A method of controlling a fluid pump, the method comprising: receiving an input indicative of a desired pressure at a fluid gun operably coupled to the fluid pump; receiving from a pressure sensor a signal indicative of pressure at the fluid gun as the pressure at the fluid gun rises upon activation of a power source operably coupled to the fluid pump via a transmission including a plurality gears; determining a desired operating speed of the fluid pump based on the desired pressure at the fluid gun and the signal indicative of pressure at the fluid gun; determining a desired gear of the transmission based on the desired operating speed of the fluid pump; and operating the transmission in the desired gear to substantially achieve the desired pressure at the fluid gun.
 23. The method of claim 22, further including receiving a signal indicative of the operating speed of the fluid pump, wherein determining the desired operating speed of the fluid pump includes selecting one of a plurality of equations indicative of a relationship between pressure at the fluid gun and fluid pump operating speed that most closely corresponds to a relationship between the signal indicative of pressure at the fluid gun and the signal indicative of the operating speed of the fluid pump.
 24. The method of claim 22, wherein determining the desired gear includes using a look-up table to select the desired gear based on the desired operating speed of the fluid pump, wherein the look-up table lists a desired gear for each of a plurality of ranges of desired operating speeds of the fluid pump.
 25. The method of claim 22, further including engaging a lock-up clutch operably coupled to the transmission.
 26. The method of claim 22, further including operating the fluid pump at a speed within a range of the desired operating speed of the fluid pump via control of the power source.
 27. A system for discharging pressurized fluid, the system comprising: a combustion engine configured to supply torque; a multi-gear transmission operably coupled to the combustion engine via a torque converter; a reciprocating fluid pump operably coupled to the transmission, the reciprocating fluid pump being configured to supply fluid to a fluid gun; a fluid gun operably coupled to the fluid pump, the fluid gun being configured to discharge pressurized fluid; a pressure sensor operably coupled to the fluid gun; and a controller operably coupled to the power source and the transmission, wherein the controller is configured to receive an input indicative of a desired pressure at the fluid gun, receive a signal indicative of pressure at the fluid gun, determine a desired operating speed of the fluid pump based on the desired pressure at the fluid gun and the signal indicative of pressure at the fluid gun, determine a desired gear of the transmission based on the desired operating speed of the fluid pump, and control operation of at least one of the power source and the transmission such that the desired pressure at the fluid gun is substantially achieved. 